Background/Purpose: The measurement of disease activity level is of central importance in the evaluation of the patient with juvenile idiopathic arthritis (JIA). The Juvenile Arthritis Disease Activity Score (JADAS) and its clinical version excluding the acute phase reactant (cJADAS) were validated and are increasingly used in clinical trials and routine practice. To allow score interpretation, cutoffs have been developed and subsequently validated for JADAS10 and cJADAS10 in RF- polyarthritis and oligoarthritis. The need to have cutoffs for other arthritis categories is increasingly evident.

To validate the JADAS10 and cJADAS10 disease activity state cutoffs to separate the states of inactive disease (ID), minimal disease activity (MiDA), moderate disease activity (MoDA), and high disease activity (HDA) in children with RF+ polyarthritis, PsA and ERA.

Methods: JIA children from 49 countries included in the EPidemiology, treatment and Outcome of Childhood Arthritis (EPOCA) study were considered. For PsA and ERA, the decision on whether to use oligoarthritis or polyarthritis cutoffs was based on the most frequent pattern of joint involvement at visit. Discriminative ability was assessed by calculating and comparing in each disease activity state the level of pain (0-10 VAS) and functional ability impairment (measured with the Juvenile Arthritis Functional Ability Score, JAFS, 0-45) and the frequency of patients satisfied with current disease state, starting a new medication, and having morning stiffness. Comparisons of quantitative variables among groups were made by Kruskal-Wallis test; Dunn’s test was used to assess differences between pairs of patient groups. Percentage data were compared by chi-squared test or Fisher’s exact test. Bonferroni’s adjustment was applied to explore post-hoc differences between pairs of patient groups.

Results: 309 children with PsA, 959 with ERA, and 382 with RF+ polyarthritis were included. 88% children with PsA and 91% with ERA had oligoarticular disease, at study visit; therefore, oligoarthritis cutoffs were used for these categories.

The level of pain and functional ability was significantly different among the JADAS-based disease states, with pain and JAFS scores increasing progressively from ID to HDA (Kruskal-Wallis test p < 0.001). The percentage of patients who prescribed a new medication, with morning stiffness < 15 minutes, and who were satisfied with current disease state were different in the JADAS-based disease states. Paired comparison showed significant discrimination for most comparisons.

Conclusion: Both the JADAS10 and cJADAS10 cutoffs to define disease activity states validated for oligoarthritis and polyarthritis showed good discriminative validity in RF+ polyarthritis, PsA and ERA. These results preliminarily indicate that available cutoffs might be used for these categories of JIA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/jadas10-and-cjadas10-based-disease-activity-states-for-psoriatic-arthritis-enthesitis-related-arthritis-and-rf-polyarthritis/